The present invention relates to an inspection apparatus for inspecting surfaces of a patterned media disk, in particular to an inspection apparatus and an inspection method suitable for optically inspecting scratches and foreign objects on both sides of a patterned media disk.
In recent years, an amount of information stored on a hard disk, which is used as a recording medium of a personal computer (PC), server, mobile device, and the like, significantly increases, and to cope with this, a perpendicular magnetic recording method is developed as a high density recording method. Currently, it is required to further improve recording density of hard disks. However, in the perpendicular magnetic recording method, as the recording density increases, the influence of magnetic interference between adjacent tracks becomes considerable. As a next-generation recording method to solve the above problem, a patterned media, which is a recording medium made by forming a pattern on a surface of a disk, is studied.
To form patterned media, nanoimprint technology is studied in which a nano-meter level pattern can be mass produced at low cost. In the nanoimprint technology, a pattern formed on a material is pressed onto a disk, on both sides of which a magnetic film layer is formed and a resist is coated thereon, the pattern shape on the material is transferred to the resist, the resist is exposed and developed, and an etching process is performed, so that a pattern of magnetic film layer is formed on both sides of the disk.
When inspecting a pattern of a patterned media disk formed in this way, inspection time increases because smaller defects need to be detected as compared with related art. However, the throughput of the inspection needs to be maintained at the same level as that in related art. To cope with this, it is necessary to shorten handling time to take a patterned media disk in and out an inspection apparatus and reverse a substrate.
A magnetic film is formed on both sides of a substrate of a magnetic disk including a patterned media disk, so that both sides of the substrate needs to be inspected at the same level of accuracy. To inspect both sides, a method is performed in which one side of the substrate is inspected first, then the substrate is reversed, and the other side is inspected. As a method for sequentially inspecting two sides of the substrate one by one, Japanese Patent Application Laid-Open Publication No. 2008-32415 (Patent Document 1) describes a configuration in which, in an inspection apparatus including a handling robot and two spindles, the handling robot reverses a disk, which is mounted on a first spindle and one side of which has been inspected, mounts the disk on a second spindle, removes the disk from the second spindle when the other side has been inspected, and conveys the disk to an ejection position.
Japanese Patent Application Laid-Open Publication No. 11-183394 (Patent Document 2) describes a disk surface inspection apparatus in which two inspection devices are included and front surfaces of two disks are inspected at the same time by one inspection device, and thereafter the disks are reversed by a reversing device and back surfaces of two disks are inspected at the same time by the other inspection device.